As dramatists get older, less is more. Caryl Churchill follows Beckett and Pinter into the field of fertile minimalism. Her last play, Here We Go, was a 45-minute meditation on death and dying. Her new one, running for an hour, juxtaposes two sharply contrasting worlds: a sunlit garden, where four women sit pleasurably conversing, and a rapidly disintegrating planet. Like all late Churchill, it packs an amazing amount into a modest frame.

The starting point could hardly be simpler. The nosy Mrs Jarrett pops through a fence into a back garden to join three women she vaguely knows. But Churchill shrewdly characterises the septuagenarian trio through their afternoon chats. Vi, an ex-hairdresser, is the most vituperative and has a criminal past it would be a pity to enlarge upon. Sally, who worked in medicine, is haunted by a fear of cats that you might call her pet aversion. Lena, meanwhile, is a one-time office worker afflicted by an agoraphobia that makes a trip to the supermarket a big deal. Over the course of the hour you get to know and like the women, who chat about everything under the sun, from families to the future.

Their talk is punctuated, however, by a series of monologues in which Mrs Jarrett, against a sizzling electrified frame, delivers a vision of global catastrophe. She starts with a terrifying image of cannibalistic underground communities. She later dwells on the devastating consequences of flood, fire, thirst and starvation, although the picture of dystopian disaster is sometimes shot through with a macabre humour. At one point, she imagines a world in which the hunger began when 80% of food was diverted to TV studios and “commuters watched breakfast on iPlayer on their way to work”.

This is not the first time Churchill has used drama to jolt us into an awareness of apocalypse. In The Skriker (1994), there is a moving speech about the erosion of our faith that spring will always return even after we are gone. And Far Away (2000) ends with a picture of the natural world in chaos. But, while the title of Churchill’s new play derives from the book of Job and raises the question of whether our planet’s decline is manmade rather than divinely ordained, I find Mrs Jarrett’s speeches less effective as they go along. There are seven of them in all and, although they are excellently delivered by Linda Bassett without any colouring of hysteria, the law of diminishing returns sets in.

The overwhelming strength of the play lies in its portrait of the women in the garden. They talk inevitably of old times: of vanishing corner shops and TV soaps. At one point they even break, with glorious spontaneity, into a rendering of the old Crystals hit from 1973, Da Doo Ron Ron. But these women are not stuck in the past. They relish the benefits of living today: “whole worlds in your pocket”, says Vi of mobile phones.

Churchill also realises the old have aspirations, too – at one point they dwell on the joys of flight – and are not without a mocking humour. “Always wanted to go to Japan,” says the hermetic Lena, to which Sally sharply retorts: “Get to Tesco first.” This is Churchill at her best, observing with wry compassion how people actually talk.

James Macdonald’s production also brings pitch-perfect performances from all the women. The great June Watson invests Vi with a wonderful mixture of tart-tongued vigour and hunger for knowledge. Kika Markham as Lena has just the right air of withdrawn shyness, though resentful of any reference to her affliction. Deborah Findlay as their host, Sally, exudes both panic and charm and, like all grandparents, casually boasts about her progeny. These garden scenes beautifully counterpoint the prophecies of disaster and lead me to think that the ever-adventurous Churchill, in her exploration of contradictions, would endorse a late remark of Harold Pinter: “Life is beautiful but the world is hell.”